Fast burning fuels containing mercaptan-peroxide reaction products



United States Patent 3,155,555 FAST BURNING FUELS C(JNTAINING MERCAP- TAN-PERGXIDE REACTIGN PRGDUCTS John E. Mahau and Cleveland R. Scott, Bartlesville, 01th., assignors to Phillips Petroleum Company, a corporation of Delaware No Drawing. Filed Aug. 11, 1952, Ser. No. 303,814

22 Claims. ((31. 149-46) This invention relates to fuels. In one of its aspects this invention relates to fuels for rocket and/or jet propulsion motors. In another of its aspects this invention relates to fuels and propellants for projectiles, missiles, jato units and the like. In another of its aspects this invention relates to solid, liquid-solid and liquid compositions of matter useful as fuels and propellants. In still another of its more specific aspects this invention relates to propellants comprising an oxidant and a fuel therefor and to a method for the preparation thereof.

Special fuels and rocket propellan s have achieved considerable military and civil importance. Rocket or jet propulsion motors of the type in which the compositions of this invention may be employed, can be used to assist take-oif of a heavily loaded plane or to propel missiles. Jet propulsion motors of the type which employ the compositions of this invention can also be used in other situations as an auxiliary to a conventional power plant where an extra surge is required. In one of the most convenient type of such jet propulsion or rocket motors, the fuel is located in the combustion chamber itself and is burned with the aid of an oxidizer, homogeneously and intimately admixed therewith, thus avoiding the need for complicated feeding arrangements for the :fuel and oxidant.

It is an object of this invention to provide new compositions of matter. It is another object of this invention to provide a fuel or rocket propellant comprising an oxidant and a fuel. It is a still more specific object of this invent-ion to provide a solid rocket propellant comprising a solid oxidant and a solid fuel therefor and to provide a method for the manufacture of such propellants. These and other objects of this invention will become apparent and suggest themselves from the accompanying disclosure. In at least one embodiment of this invention at least one of these objects will be achieved.

It has now been discovered that compositions compristing an oxidant and the reaction product of an unsaturated aliphatic mercaptan :with a peroxide are useful as fuels or propellants. By the term peroxide as used herein, we mean to include also hydroperoxides. The above-referred reaction product which is a component of the compositions of this invention is more fully and completely disclosed in the copending patent application of A. L. Ayers and C. R. Scott, Serial No. 264,832, filed January 3, 1952. The disclosures of this above-identified patent application relative to these reaction products are herewith incorporated and made a part of this disclosure.

The oxidants which are employed in the practice of this invention are those oxygen-containing materials which are commonly employed as oxidizing agents or are capable of acting as such. It is a characteristic of these materials that they readily give up oxygen, such as upon being heated, to produce gaseous oxygen or when reacted with another material, transfer with an accompanying chemical reaction oxygen to another material. Solid oxidants are preferred in the practice of this invention. However solutions (such as aqueous solutions of these solid oxidants) or liquid oxidants such as hydrogen peroxide and its solutions as well as the various per-acids, such as persulfuric acid, peracetic acid and the like where suitable, are also applicable in the practice of this invention. Fuming nitric acid is also a suitable oxidant.

Solid oxidants or mixtures thereof, either with other solid oxidants or liquid oxidants, include the ammonium and alkali metal compounds of the nitrates, chlorates, perchlorates, chlorites, hypochlorites, dichromates, chromates, chromites, perborates, permanganates and the like. The corresponding alkaline earth metals, such as calcium, strontium, magnesium and barium, as well as the aluminum, boron and the like, compounds are also useful. Specific solid oxidants which are useful in the compositions of this invention include ammonium nitrate, ammonium perchlorate, ammonium chlorate, sodium nitrate, sodium perchlorate, lithium chromate, lithium perborate, lithium chlorate, potassium permanganate, potassium chlorate, potassium nitrate, potassium perchlorate, calcium nitrate, calcium perchlorate, barium peroxide, sodium peroxide, calcium peroxide, aluminum nitrate, aluminum perchlorate, sodium perborate, etc.

In accordance with this invention the oxidant component of the compositions is intimately admixed and blended with the fuel component (reaction product of an unsaturated aliphatic mercaptan with a peroxide) to yield a homogeneous intimate admixture. If solid oxidants are employed it is preferred that these solid oxidants b powdered to sizes finer than about 159406 mesh. The oxidant is then admixed with the reaction product to form a homogeneous mixture, such as a. paste or solid mass.

The amount of oxidant in the compositions of this invention is usually a major amount of the total admixture, generally in the range from about 50 to about percent by Weight of the total admixture. Of course, if desired, a minor amount of oxidant, less than 50 percent by weight, usually not below 20 percent by weight of the total admixture can be employed. Often times it is p-re tferred that the reaction product make up about 4-0 to 65 percent by weight of the total admixture.

The reaction product of an unsaturated aliphatic mercaptan and peroxide, which is employed as the fuel c mponent of the compositions of this invention may be derived from any suitable source. Those unsaturated aliphatic mercaptans which contain from 3 to 10 carbon atoms, inclusive, are particularly useful in the preparation of the reaction products employed in the practice of this invention. Specific, useful, unsaturated aliphatic mercaptans are allyl mercaptan, isopropenyl mercaptan, A -butenyl mercaptan, A -butenyl mercaptan, A' butenyl mercaptan, isobutenyl mercaptan, the various other butenyl, pentenyl, hexenyl, hepteny-l, octenyl, n-onenyl and deoenyl mercaptans as well as the corresponding dienyl mercaptans. The unsaturated aliphatic mercaptans may contain more than one double bond or one or more triple bonds such as are obtained from an acetylene derivative, e.g. a butynyl mercaptan. In general the alkenyl mercaptans, alkynyl mercaptans, alkadienyl mercaptans, either straight or branched chain, which contain from 3 to 10 carbon atoms are suitable. Also, if desired nonhydrocarbon substituents such as a hydroxy group, a nitro group or other oxygen containing group may be present in these unsaturated aliphatic mercaptans, provided of course they are substantially inert and/or also do not appreciably affect the reaction for the production of these reaction products.

The peroxides which are used in the production of the reaction product fuel component of this invention include the various inorganic and organic peroxides, necessarily including the hydroperoxides. Typically suitable peroxides are hydrogen peroxide, sodium peroxide, lithium peroxide, potassium peroxide, barium peroxide, benzoyl peroxide, acetyl peroxide, triethylmethyl hydroperoxide, tniethylmethyl peroxide, tert-butyl peroxide, tert-butyl hydroperoxide, tetralin hydroperoxide, tetralin peroxide, 1- methyl cyclohexyl hydi'operoxide, isopropyl peroxide, phenylcyclohexyl hydroperoxide, dimethyldecylhydroperoxymethane, tert-butyl isopropylbenzene hydroperoxide, acetyl benzene peroxide, benzoyl hydroperoxide, acetone peroxide, olefin peroxides, and the like. The peroxides which are suitable may be represented by the empirical formula M wherein M is an alkali metal, eg. sodium, potassium, lithium, by the empirical formula M'O where M is an alkaline earth metal, e.g., barium, strontium, calcium, and by the empirical formula R 0 wherein R is a hydrogen atom or an organic radical. Those materials which can be represented as having the empirical formula RO H are generally known as hydroperoxides and those materials which can be represented as having the empirical formula R 0 are generally known as peroxides, however the term peroxide as used herein is meant to include not only peroxides but also hydroperoxides. R is preferably a hydrocarbyl (containing only carbon and hydrogen atoms) radical and can be an alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloaliphatic such as cycloalkyl, cycloalkenyl, and the like, radical. The Rs in any R 0 can of course be of a mixed character i.e. one R an alkyl radical and the other R an aryl or cycloaliphatic radical, or hydrogen. Also the organic radical R may contain if desired non-hydrocarbon substituents such as a nitrogroup, hydroxy group, halogen atom, sulfur-containing group, and the like. It is preferred, however, when using organic peroxides or hydroperoxides that the total number of carbon atoms in the empirical formula R 0 wherein R is an organic radical or hydrogen, at least one R being an organic radical, be not less than 4 and not more than 24.

The reaction product of an unsaturated mercaptan with a peroxide is produced by the addition of a peroxide thereto. The reaction, once started is exothermic. In some cases the reaction is spontaneous at room temperature while in others the reaction mixture must be gently warmed to initiate reaction. The reaction temperature can of course be varied and usually is within the range 30 F. to 200 F., although higher and lower temperatures may be used. The time required to complete the reaction is usually very short, depending to some extent upon the temperature, and can vary from a few seconds to about 30 minutes or more.

The reaction product obtained can vary from heavy, viscous fluids to hard, resin-like solids. The degree of hardness of the reaction product materials can be varied by varying the mol ratio of the unsaturated aliphatic mercaptan to the peroxide. In general when the mol ratio of the peroxide to mercaptan is high, above about 1:1 the reaction product is a hard, insoluble resin. When the ratio of peroxide to mercaptan is about 1:1 a waxy oil or petrolatum-like reaction product is obtained. Usually the reaction is carried out with a peroxide to mercaptan mol ratio of from about 1:1 to about 8:1.

The reaction products, if solid, are somewhat thermoplastic and can be extruded. In the preparation of the propellant compositions of this invention the reaction product is first prepared in form suitable for use as desired. When employing a solid reaction product material,

the solid material is preferably ground to a fine powder and then admixed and blended with the oxidant. The resulting admixture may then be pressed or formed into suitable shapes. When employing resinous reaction product materials or materials which have the consistency of heavy viscous oils or the like, propellant compositions of this invention can be made by milling or stirring together the resinous materials and oxidant in the desired ratios.

Compositions of this invention can be formed into pellets or grains for use in rocket motors or as propellants for projectiles by compression molding techniques, care being exercised during the molding process to maintain the temperature of the composition below the deflagration point of the composition.

In addition to the oxidant and reaction product (fuel) components of the compositions of this invention, other materials may be added thereto, such as oxidation catalysts e.g. ferric chloride, cobalt naphthenates, in order to promote and to provide uniform, rapid combustion of the fuel. Binding agents and similar materials such as asphalt and the like can also be incorporated, usually up to about 25-40% by Wt. of the entire mixture, so that the entire composition can be cast or molded into pellets or grains of a strong, coherent nature particularly suited for use as a rocket and projectile propellants.

The following examples are illustrative of the invention and the practice thereof. These examples are presented so that a better understanding of this invention may be had and are in no sense limitive of this invention.

Example I Allyl mercaptan and 30 percent aqueous hydrogen peroxide in approximately equimolar amounts were added to a flask and gently heatd. An extremely exothermic reaction ensued and a white resin-like material was formed which was thermoplastic.

A sample of the resin was ground to a powder (100 mesh) and admixed with potassium chlorate on a weight basis of 2 parts resin to 3 parts potassium chlorate. The composition exhibited rapid burning characteristics.

Example 11 2 cc. of allyl mercaptan (0.025 mol based on an assumed density of 0.93 for allyl mercaptan) were mixed with 5 cc. of 30 percent hydrogen peroxide (0.065 mol) and warmed sufliciently to start the reaction. This mixture of hydrogen peroxide and allyl mercaptan in a ratio of 3 mols of hydrogen peroxide to 1 mol of mercaptan gave a very vigorous exothermic reaction, and to the formation of a very hard resin.

A sample of the resin was ground to 100 mesh and admixed with potassium chlorate in a weight ratio of 2 parts resin to 3 parts potassium chlorate.

The composition exhibited rapid burning characteristics.

Example III 2 cc. of allyl mercaptan (0.025 mol) were admixed with 2 cc. of 30 percent hydrogen peroxide (0.026 mol) and warmed sufiiciently to start the reaction. A petrolatumlike product was formed which was white in color.

A sample of the resin was admixed with potassium chlorate on a weight basis of 2 parts resin to 3 parts potassium chlorate. The composition exhibited rapid burning characteristics.

Example IV Allyl mercaptan and benzoyl peroxide in a mol ratio of between 1:5 and 1:6 were added to a flask and heated to a temperature in the range of 100 to 200 F. A dark resinous solid was formed.

A sample of the resin was ground to 100 mesh and admixed with potassium chlorate on a weight basis of 2 parts of resin to 3 parts of potassium chlorate. The composition exhibited rapid burning characteristics.

Example V Allyl mercaptan and cumene hydroperoxide in a mol 0 ratio of between 1:1 and 1: 1.5 were added to a flask and chlorate on a Weight basis of 2 parts of resin to 3 parts of potassium chlorate. The composition exhibited rapid burning characteristics.

Example VI Allyl mercaptan and sodium peroxide in a mol ration of between 1:1 and 121.5 were added to a flask. O11

standing at room temperature for minutes, the mixture became very viscous.

A sample of the viscous material was admixed with potassium chlorate on a weight basis of 2 parts resin to 3 parts potassium chlorate. The composition deflagrated upon being heated.

As will be evident to those skilled in the art upon reading this disclosure, many modifications, substitutions and variations of this invention may be made without departing from the spirit or scope of this disclosure or invention.

We claim:

1. A propellant comprising from to 90 percent by weight of an oxidant and from 80 to 10 percent by weight of a fuel component consisting essentially of the reaction product of a mercaptan and a first peroxide; said oxidant being selected from the group consisting of persulfuric acid, peracetic acid, fuming nitric acid, an inorganic strong oxidizing salt, barium peroxide, calcium peroxide and hydrogen peroxide; said reaction product having been obtained by reacting said first peroxide and said mercaptan in a mol ratio of at least 1:1; said mercaptan having a structural formula of R'SH wherein R is selected from the group consisting of an acyclic carbon to carbon unsaturated hydrocarbon radical having from 3 to 10 carbon atoms, said hydrocarbon radical substituted with a nitro group, and said hydrocarbon radical substituted with a hydroxy group; said first peroxide being selected from the group consisting of M 0 MO and R 0 wherein M is an alkali metal, wherein M is an alkaline earth metal, wherein each R is selected from the group consisting of: a hydrogen atom; an alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, and cycloalkenyl radical; a nitro-substituted alkyl, aryl, alkaryl, aralkyl, alkenyl, cycioalkyl, and cycloalkenyl radical; a hydroxysubstituted alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, and cycloalkenyl radical; and a halogen substituted alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, and cycloalkenyl radical, said radicals containing from 4 to 24 carbon atoms per molecule.

2. A composition according to claim 1 wherein the acyclic unsaturated mercaptan is allyl mercaptan.

3. A composition according to claim 1 wherein the acyclic unsaturated mercaptan contains 4 carbon atoms.

4. A composition according to claim 1 wherein the first peroxide is hydrogen peroxide.

5. A composition according to claim 1 wherein the first peroxide is benzoyl peroxide.

6. A composition according to claim 1 wherein the first peroxide is cumene hydroperoxide.

7. A composition according to claim 1 wherein the first peroxide is sodium peroxide.

8. A composition according to claim 1 wherein the first peroxide is barium peroxide.

9. A composition according to claim 1 wherein the first peroxide is an organic peroxide having not more than 20 carbon atoms.

10. A composition according to claim 1 wherein the oxidant is ammonium nitrate.

11. A composition according to claim 1 wherein the oxidant is potassium chlorate.

12. A composition according to claim 1 wherein the oxidant is a solid material.

13. A composition according to claim 1 wherein the oxidant is sodium nitrate.

14. A composition according to claim 1 wherein the oxidant is ammonium nitrate, the unsaturated aliphatic mercaptan is allyl mercaptan and the peroxide is hydrogen peroxide.

15. The propellant composition of claim 1, wherein an asphalt binder is present in an amount up to 40 percent by weight of the propellant composition.

16. A composition according to claim 1, wherein the acyclic unsaturated mercaptan is A -butenyl mercaptan.

17. A composition according to claim 1, wherein the acyclic unsaturated mercaptan is A -butenyl mercaptan.

18. A composition according to claim 1, wherein the acyclic unsaturated mercaptan is isobutenyl mercaptan.

19. A composition according to claim 1, wherein said acyclic unsaturated mercaptan is isopropenyl mercaptan.

20. A composition according to claim 1, wherein the oxidant is ammonium perchlorate.

21. A composition according to claim 1, wherein the oxidant is potassium perchlorate.

22. A method for preparing a composition useful as a propellant comprising reacting a mercaptan with a first peroxide in a mol ratio of from 1:1 to 1:8 to yield a reaction product, and admixing with said reaction product an oxidant in an amount from about 20 to percent by weight of said composition; said oxidant being selected from the group consisting of persulfuric acid, peracetic acid, fuming nitric acid, an inorganic strong oxidizing salt, barium peroxide, calcium peroxide and hydrogen peroxide; said mercaptan having a structural formula of R'SH wherein R is selected from the group consisting of an acyclic carbon to carbon unsaturated hydrocarbon radical having from 3 to 10 carbon atoms, said hydrocarbon radical substituted with a nitro group, and said hydrocarbon radical substituted with a hydroxy group; said first peroxide being selected from the group consisting of M 0 M'O and R 0 wherein M is an alkali metal, wherein M is an alkaline earth metal, wherein each R is selected from the group consisting of: a hydrogen atom; an alkyl, aryl, alkaryl, arallryl, alkenyl, cycloalkyl, and cycloalkenyl radical; a nitro-substituted alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, and cycloalkenyl radical; a hydroxy substituted alkyl, aryl, alkaryl, aralkyl, alirenyl, cycloalkyl, and cycloalkenyl radical; and a halogen substituted alkyi, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, and cycloalkenyl radical, said radicals continuing from 4 to 24 carbon atoms per molecule.

References Qited in the file of this patent UNITED STATES PATENTS 2,097,155 Groll Oct. 26, 1937 2,125,649 Reppe Aug. 2, 1938 2,125,685 Nicodemus Aug. 2, 1938 2,136,178 Carothers Nov. 8, 1938 2,479,828 Geckler Aug. 23, 1949 2,594,579 Novotny Apr. 29, 1952 OTHER REFERENCES Braun in Berichte, vol. 59, pp. 1207-1209 (1926), 260, 79.7. 

1. A PROPELLANT COMPRISING FROM 20 TO 90 PERCENT BY WEIGHT OF AN OXIDANT AND FROM 80 TO 10 PERCENT BY WEIGHT OF A FUEL COMPONENT CONSISTING ESSENTIALLY OF THE REACTION PRODUCT OF A MERCAPTAN AND A FIRST PEROXIDE; SAID OXIDANT BEING SELECTED FROM THE GROUP CONSISTING OF PERSULFURIC ACID, PERACETIC ACID, FUMING NITRIC ACID, AN INORGANIC STRON OXIDIZING SALT, BARIUM PEROXIDE, CALCIUM PEROXIDE AND HYDROGEN PEROXIDE; SAID REACTION PRODUCT HAVING BEEN OBTAINED BY REACTING SAID FIRST PEROXIDE AND SAID MERCAPTAN IN A MOL RATIO OF AT LEAST 1:1; SAID MERCAPTAN HAVING A STRUCTURAL FORMULA OF R''SH WHEREIN R'' IS SELECTED FROM THE GROUP CONSISTING OF AN ACYCLIC CARBON TO CARBON UNSATURATED HYDROCARBON RADICAL HAVING FROM 3 TO 10 CARBON ATOMS, SAID HYDROCARBON RADICAL SUBSTITUTED WITH A NITRO GROUP, AND SAID HYDROCARBON RADICAL SUBSTITUTED WITH A HYDROXY GROUP; SAID FIRST PEROXIDE BEING SELECTED FROM THE GROUP CONSISTING OF M2O2, M''O2, AND R2O2, WHEREIN M IS AN ALKALI METAL, WHEREIN M'' IS AN ALKALINE EARTH METAL, WHEREIN EACH R IS SELECTED FROM THE GROUP CONSISTING OF: A HYDROGEN ATOM; AN ALKYL, ARYL, ALKARYL, ARALKYL, ALKENYL, CYCLOALKENYL RADICAL; A HYDROXYSUBSTITUTED ALKYL, ARYL, ALKARYL, ARALKYL, ALKENYL, CYCLOALKYL, AND CYCLOALKENYL RADICAL; AND A HALOGEN SUBSTITUTED ALKYL, ARYL, ALKARYL, ARALKYL, ALKENYL, CYCLOALKYL, AND CYCLOALKENYL RADICAL, SAID RADICALS CONTAINING FROM 4 TO 24 CARBON ATOMS PER MOLECULE. 